21303997 has 16 divisors (see below), whose sum is σ = 26349120. Its totient is φ = 16934400.

The previous prime is 21303979. The next prime is 21304001. The reversal of 21303997 is 79930312.

It is a cyclic number.

It is not a de Polignac number, because 21303997 - 2¹¹ = 21301949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21303917) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1204 + ... + 6637.

It is an arithmetic number, because the mean of its divisors is an integer number (1646820).

Almost surely, 2^21303997 is an apocalyptic number.

It is an amenable number.

21303997 is a deficient number, since it is larger than the sum of its proper divisors (5045123).

21303997 is a wasteful number, since it uses less digits than its factorization.

21303997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7884.

The product of its (nonzero) digits is 10206, while the sum is 34.

The square root of 21303997 is about 4615.6253097495. The cubic root of 21303997 is about 277.2173221880.

The spelling of 21303997 in words is "twenty-one million, three hundred three thousand, nine hundred ninety-seven".